The present invention relates to a new and improved multiple strand elastic means. More particularly, the present invention relates to a means for adhering multiple strands of elastic in a product such as a disposable diaper product.
Disposable diaper products have been known for some time. A disposable diaper product generally consists of a liquid-impermeable backing sheet, a liquid-permeable facing sheet, and an absorbent core laminated between the facing and backing sheets. Initially, in many of these products the absorbent core consisted of "wadding" or plies of tissue. Diapers utilizing such an absorbent core are disclosed in U.S. Pat. No. Re. 26,151.
The wadding type of batt or core was replaced for the most part by an improved absorbent batt which generally comprises what is termed "fluffed wood pulp fibers". This absorbent batt which is a layer of individualized wood pulp fibers has substantial thickness. A diaper which incorporates such a fluffed wood pulp absorbent batt is described in U.S. Pat. No. 2,788,003. This diaper had improved absorbent capacity and somewhat better containment than a diaper using a wadding layer. Also, the fluffed wood pulp layer is quite soft, flexible, and conformable, and hence produces an improved diaper as to the feeling and softness.
Even though the fluffed wood pulp absorbent batts improve the capacity of the disposable diaper, they remain quite thick. Such thickness provides a problem with respect to containment of the liquid, and thus, the clothes of the infant may become wet and/or stained.
One answer for leaking diapers provided in the marketplace has been the elastic-leg diapers or stretch diapers. Though these diapers provide no better absorbent batt than previous diapers, they have indicated improved containment of liquid. Such diapers are disclosed and described in U.S. Pat. Nos. 3,860,003; 4,050,462; 4,324,245; and 4,430,086. Though the containment features are better than the prior art products, the elasticized products of these patents and those in the marketplace at the present time fit more tightly permitting less air circulation. Frequently, this can become irritating to the skin and the tighter the elastic or the more close fitting the diaper, the greater the irritation. This is especially true adjacent the area where the elastic leg portion of the product contacts the wearer.
Furthermore, the adherence of the elastic to the backing, or facing, or both, has been a problem in the art. For instance, U.S. Pat. No. 4,081,301 attempts to solve the problem of adhering elastic by intermittently applying adhesive to the elastic, adhering the elastic member to the facing or the backing of a disposable diaper product, and then severing the elastic in the unadhered portion. In this method and others known similar to it, it has been deemed necessary to provide adhesive along substantially the entire length of the elastic member where it is desirable to adhere the elastic. The addition of adhesive along the stretched portion of the elastic provides an additional thickness to the elastic and at least partially interferes with the gathering power of the elastic member.
The present invention provides a new and improved means for adhering multiple strands of elastic in a disposable diaper product. The new means of adhering the elastic saves a large amount of adhesive, provides a very soft gathering zone, provides uniformity in the gathering of the elastic member, and couples the motion of the surronding fabric to the elastic. Furthermore, it is particularly suitable for providing breathability in the elastic zone.